Lighting unit.



W. HARRISON. LIGHTING UN|T- APPLICATION FILED ra.2o. m2.

1,299,936. Patented Apr. 8,1919.

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' sphere UNITED STATES PATENT OFFICE.

WARD HARRISON,

OF EAST CLEVELAND, OHIO, ASSIGNOB. 'I'O GENERAL ELEOTRI GOMPANY, A CORPORATION OF NEW YORK.

LIGHTING UNIT.

Specification of Letters Patent.

Patented Apr. 8, 1919.

Application flied February 20, 1917. Serial No. 149,928. 5

To all whom it may] concern:

' Be it known that I, WARD HARRISON, a citizen of the United States, residing at East Cleveland, in the county of Cuyahoga, State of Ohio, have invented certain new and useful Improvements in Lighting Units, of which the following is a specification.

My invention has reference to improvements in lighting units, designed to overcome the defects of fixtures, heretofore used.

When an intense source of light is used in a lightin fixture, the transmission of light is usua ly modified by shades refractors, globes, etc., with the view of directing the light to regions where the illumination is mostly1 needed, and diverting it from regions w ere the illumination is either not required or is objectionable. Thus, for instance, in street lighting the aim is to direct thev main part of the light to the hemibelow the horizontal plane assed through the source, and it is desirable in this case to avoid the glare which the direct rays from the source would produce. For all these purposes it has been suggested that refractors of definite geometrical design be placed in the nth of the rays from the source by whic indeed the light was directed, mainly below the horizontalplane. In addition to this, or independently thereof, a diffusing lobe, either opalized or sandblasted or etc ed was use whereby the source of light as such became practically invisible. The fixture acted upon the eye as if the difiusing medium. itself were the source of light, that is to say a much larger source'of 1i ht which there ore had only a comparative y low intrinsic luminosity. All this was desirable, but a great loss of light resulted from the use of such globes. The difl'using glo'be alone, without the refractin medium was mainly used in connection wit a light source, which, without the aid of refractors directed the light rays into the desired region below the horizontal plane. Of these sources of light the magnetic lamp is a good exam is.

The opa ized globes absorb a great portion of the light emitted by the source. The sand-blasted or etched globes absorb less of the light emitted by the source, but have the objections that the light transmitted therethrough is more or less streaked. Moreover in practice such globes have proven impossible to keep presentabl clean.

By my invention these ifiimllties are overcome 'by the use of a globe in combination with a refractor. The globe is formed by molding into its surface rather small protuberances and depressions, whereby each protuberance is more or less rounded and merges into the depressions in a smooth and gradual manner. The light passing through such a globe is not resolved into its elements, since all sharp edges formed by the intersection of smal plane surfaces are absent. Globes of this character absorb less of the light received by the same than either the opalized or the sand-blasted or etched glass globes. But transmitted in a direction, at or below the horizontal, these globes do not appreciably modify the directionof the rays. When such globe is used in conjunction with a definite refractor the refracting rays reaching the globe retain the generaldirection given to the same by the refractor.

For a better understanding of my improved lighting unit reference may be had to the illustrations accompanying this specification. Figure l of which shows one ty e of unit embodying my invention; Fig. 2 s ows another type of unit; Fig. 3 is an enlarged sectional view of a portion of the protective globe illustrating the directions of a number of light rays passing therethrough.

Referring to Fig. 1, the lower art of a fixture is shown which is particular y adapted to the housing of a. high efiiciency incandescent lamp 1. Closely surroun iug the lamp bulb is a band refractor 2, the latter being supported in any convenient manner, as for instance by strips 3, which engage an annular shoulder on the top of the refractor and are equally spaced apart by a suitable spacing ring as shown. The upper ends of strips 3 are conveniently bolted to downwardly depending supporting strips 4, and between the adjacent ends of these strips is secured a reflector 5 which "is" adap ed to intercept the upward rays and dine them downwardly in useful directions. The reflector 5 and strips 3 and 4 are adapted to be suspended as a unit from the top of a flarware.

ing outer shell 6, it bein understood that the shell 6 is adapted to is into and be secured to a standard fixture of the type shown in Fig. 4. Surrounding the lamp 1 and band refractor 2 is a lar r outer protective and light scattering glfiie 7 which is adapted to be secured to the interior of the shell 6. A suitable dust proof packin as for instance felt 8 is located between t e upper rim of the globe 7 and the shell. In Fig. 2 is illustrated a fixture es ecially designed for street lamps which em ies also an meandescent lamp 1 and a band refractor 2, illustrated in dotted lines, which are inclosed within an outer globe 7 In this case the globe 7 consists of a number of glass panes suitably assembled together to form a closure of octa. onal contour; In both cases the globe embodies on its interior su face rcfracting media for producing irre lar refraction or bending of the rays in every imaginable direction. These refracting media consist, as shown in Fig. 3 on an exaggerated scale, of a multiplicity of minute merging hills 9 and valleys 10. The rays of light 11in passing through the globes are bent in various directions in some such manner as is indicated in the vertical plane illustrated in F i 3, from which it will be aparent that t e general direction of the rays efore encountering the globe is substantially preserved. It is understood that these hills and valleys are of suchsmall dimensions and so numerous that practically every t ray entering the glass encounters the g ass at an inclination difl'erent from every other ray and at an inclination so small as to avoid internal reflections and consequent internal losses which are especially noticeable in rismatic and other diffusing glassu bstantially every ray is transmitrough the globe as indicated in Fig. 3, and the efliciency, therefore, of transmission is practically the same as if both surfaces 0 the glass were plain, whereas the irregular refraction indicated results in the blurring of the most intense light source in such a manner that its. outlines are obhterated and the unit is rendered leasing and harmless to the eyes of the e irregular refractor or globe, therefore,

ted th particularly industrial lighting. s said above, these irregularly formed hills 9 and valleys 10 are the interior of ing media by pressing results in the elimination of sharp points and crevices, which in the sand-blasted and etched and prismatic glassware, in addition to causing streaking cause considerable inconvenience, due to the difliculty of dislocatin dirt and foreign matter collected therein. Furthermore losses by internal reflections are avoided and the characteristic lifeless appearance of diffusing glass is eliminated. It is understood that one of the coiiperatin mold forms used in making the glassware as i lar hills and valleys formed thereon which correspond to the refractin media 9 and 10 illustrated in Fig. 3. In t e case of the ancs 7 illustrated in Figs. 2 and 3 these re cting media are incorporated in the rolling or pressing process, globe illustrated in Fig. 1, this is accomplished in the pressing operation by incorporating on the plunger of the mold an irregular surface whic corresponds to the irregularly refracting surface formed on the interior of the globe. The moldmaker goes over the entire surface of the plunger with some convenient tool, as for instance, a chisel or milling tool, and forms thereon numerous little depressions, or cavities, as close together as it is practicable to make them, these little depressions corresponding to the hills or 'bulbul-ar projections 9 formed on the glass globe. These depressions or indentations on the plunger iterally cover the entire surface and are made of small dimensions for a double purpose. In the first place, the stickin of the plunger durin the processof mol ing the globe is entire y avoided, by making the depth of the depressions as small as pos sible, and, second, the resultant minature refracting media on the interior of the lobe, while producing irregular refraction, (50 not give rise to interna reflections and there are no resultant sharp points or crevices to interfere with the cleaning of the globe.

It has been found that the appearance of the globe may be somewhat improved by incorporating a very slight amount of white coloring material in the glass batch from it is ]made s i t y opa -%Vhat I claim as new and desire to secure by Letters Patent of the United States, is

and in the case of the.

so as to make the globe.

1. A lighting fixture for housing a highly intense artificial light source comprising a band refractor closely surrounding the source for modifyin the distribution of the light rays and a arger outer rotective inclosing glass globe surroun mg said source and refractor and having inco rated therein media for producing diifusion of the li ht rays without impairing the directiona value of the unit.

2, A lighting firture comprising n artificial light source, a prismatic refraetor surrounding said light source shaped to direct the light rays from said source in a desired general direction, and a diffusing element in the path of the directed li ht rays provided with protuberances and epressions which gradually merge into each other whereby the light rays received by said element are caused to pass through the same without substantial deviation from the general direc- 10 tion given to them by the directing means.

In witness whereof, I have hereunto set my hand this 17th day of February, 1917.

WARD HARRISON;

It. is hereby certified that in Letters Patent No. 1,299,936, granted April 8, 1919,

upon the application of Ward Harrison, of East Cleveland, Ohio, fo an improvement in "Lighting Units," an error appeais in the printed specification requiring correction as follows: Page 1,1ine 46, for the word magnetic read magnetite;

and that the said Letters Patent should be read with this correction therein that.

the same may conform to the record of the ease in the Patent. Ofliee.

' Signed and sealed this 6th day of May, A. D., 1919.

R. F. WHITEHEAD,

Acting Commissioner of Patents.

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